The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the inventors hereof, to the extent the work is described in this background section, as well as aspects of the description that does not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted to be prior art against the present disclosure.
Accurate time delay estimation has applications in ranging, localization, and synchronization, for example. Increased accuracy improves the abilities of wireless networks to locate nodes within its network. In some instances, location estimates are determined using distance and range estimates between nodes such as an access point and a client station. For example, in IEEE 802.11 wireless communication systems, accurate time delay estimation is important for indoor localization where the required degree of location accuracy is within centimeters rather than meters. For surveillance applications, synchronization between nodes in a network is required for reliable location estimates determined from multilateration techniques that rely on time delays received at synchronized receivers.
Time delay estimations can be obtained by calculating the group delay using the frequency response of received signals. However, this technique does not provide sufficient accuracy as required for various applications that are highly sensitive to time delay errors.